Surgical anatomy and accuracy of percutaneous achilles tendon lengthening

Percutaneous Achilles tendon lengthening is frequently done to treat gastrocsoleus equinus contracture. To our knowledge, no study has documented the proximity of tendinous or neurovascular structures to the nearest edges of each hemisection in a percutaneous Achilles tendon lengthening, the complication rates related to injury of such structures, or the Achilles tendon rupture rates from inaccurate cuts. Thus, our goal was to document these distances and determine the accuracy of this procedure.

We performed triple-hemisection percutaneous Achilles tendon lengthening (Hoke technique) in 15 cadaver specimens and documented the distance from each cut edge to various relevant anatomical structures. We also documented the accuracy of each cut (diameter of hemisection divided by total tendon diameter), with a reference goal of 50% transection at each level.

We found that percutaneous Achilles tendon lengthening is a relatively accurate procedure with hemisections averaging 50% for the middle cut and 60% at the most proximal cut, and 55% at the distal cut. Some tendinous and neurovascular structures are, on average, less than 1 cm from the nearest margin of a given hemisection and are, therefore, at risk. These included the flexor hallucis longus at the middle and proximal cuts (9.1 mm and 5.7 mm, respectively), the tibial nerve at the proximal cut (8.3 mm), and the sural nerve at the middle-lateral cut (7.9 mm).

In cadavers, reasonably accurate cuts can be made, with some vital structures less than 1 cm from the cut tendon.